The present invention relates to an improved adjustment and regulation system so that when the engine is still cold, air-fuel feed is controlled by an open-loop system and when a minimum operating temperature is attained, a closed-loop control regulating device is used.
In a known device of this kind (German Offenlegungsschrift No. 23 01 354), a monitoring device which monitors the functioning of the oxygen measuring probe used as an exhaust gas probe; if the probe is not functioning, the monitoring device deactivates the regulating device. Furthermore, a supplementary contact in the known device affords the opportunity of activating the regulating device only upon the attainment of a specified operating temperature of the internal combustion engine.
In oxygen measuring probes which operate on the principle of ion conduction by means of a solid electrolyte and whose output signals exhibit a voltage jump at an air number of .lambda.=1, the function is greatly dependent on temperature. Only after a minimum temperature has been attained does the measuring probe emit a voltage signal which is sufficiently rapid for the purposes of the subsequent regulating means.
There are known devices using an oxygen measuring probe of this kind which detect the earliest-possible operational readiness of the measuring probe and then activate or deactivate the regulating device for the fuel-air mixture of the engine accordingly (German Offenlegungsschrift No. 27 07 383). The early activation of the regulating device which is sought in this known device has the disadvantage, however, of not having the oxygen measuring probe react quickly enough to changes in the mixture composition. During idling, this condition can cause "bucking" or roughness on the part of the engine.